QUOTE(chemistry @ Oct 23 2019, 06:48 PM)
Dear @zeng
Would you be willing to review this 48hr blotter spot ? Thanks in advance.
Car make: Nissan AD Resort 1.6L Manual (Carburetor)
Odometer: 307030 km
EO in use: Mannol Diesel Extra 10w40 API CH-4/SL
EO mileage: 9771 km
Traffic conditions: 95% stop-go in town
Hi Chemistry ,
There is absence of darkened or black perimeter ring or rim surrounding the centre/deposit zone , indicating absence of or negligible amounts of insolubles or semi-solubles ,or coagulation of contaminants and pollutants within the oil eco system , that has been properly and successfully dispersed away from metal contacting surfaces as represented by the transparent and light-coloured centre zone area and its absence of opaquecity .
Taking Russian site formula for Coefficient of Dispersancy CD = 1 - ( d*d/D*D ) , where
d = outer diameter of 'gray perimeter ring,per se' inclusive of centre zone and/or part of diffussion zone , 45 mm in your picture ; and
D = outer diameter of diffussion zone (just within translucent ,fuel zone if any), being 95 mm here ,
Your CD is 0.77 which is well above the arbitrarily set oil change limit of 0.3 .
IMHO, this 9771 km used CH4/SL Mannol oil is good to carry on in service , if you so wish or comfortable .
Yes, you have some fuel dilution problem which I feel is academic and of no issue in the oil's continuing service ,yet .
Note:95% stop-go in town is classified by OEM as severe service implying oil change intervals is to be halved . However , in the absence of UOA, your blotter spot indicates the oil condition and its detergency/dispersancy capabilities is in good shape , IMO .
This post has been edited by zeng: Oct 24 2019, 11:56 AM